In the Austrian Patent Document No. 199,759, a step selector for a stepped transformer is described which comprises a plurality of fixed contacts respectively associated with the steps of a transformer in at least one plane in a wall of an electrically insulating cylinder. For each of these planes, a respective contact bridge is provided. The inner end of each contact bridge slidably engages a contact ring which is also connected in the electric circuit. The contact bridge is entrained by an arm extending generally radially from and connected to a switching shaft which is rotatable about the axis of the cylinder. The outer end of each contact bridge is engageable with the or each fixed contact lying in the aforementioned plane.
In the past, it has been necessary to attach the support arm for the contact bridge with metallic parts so that there was always the possibility of voltage jumping, excessive arc extension and the like which could be detrimental to the breakdown voltage of the selector and could lead to premature deterioration thereof.